Chicken may be left whole, or cut into pieces. Place chicken in a large soup kettle or large crock pot. Cover with the water (use more if necessary to cover, but use at least the quart and a half).
Cut celery into large pieces, and place celery with tops, onion, carrot, garlic, peppercorns and thyme or rosemary in the water around the chicken. Bring to a boil, then lower heat and simmer for one and a half hours (or cook on low power for 6 hours in the crock pot).
When chicken is very tender, remove meat from bones and save for a dish requiring cooked chicken. Leave skin and bones in water with vegetables.
Increase heat and lightly boil until liquid is reduced to about a quart (or turn to high in crock pot and cook for 2 hours uncovered).
Taste chicken stock, and add sea salt if desired. Do not make the stock as salty as you would soup to serve, because it will be used in other recipes calling for more salt. You may also omit the salt if desired.
Pour stock through a strainer into freezer containers or mason jars. Chill in refrigerator. As stock cools, any fat will rise to the top and can be skimmed off if you want a low fat stock.
When cool, cover tightly and transfer to freezer. This should keep up to 3 months in your freezer.